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No.08 2006

Mud and mangroves in the Firth of Thames

How toxic are heavy metals to estuary life?

A better picture for oil exploration

The Argonauts are back

Predicting ocean nutrient levels

The Argonauts are back

The Argonauts are back

RV Kaharoa in San Diego for fuel and provisions during the 23 186 nautical mile expedition to deploy ocean-profiling Argo floats. Kaharoa will spend the next few months conducting fisheries surveys and other research in New Zealand’s coastal waters, before its next Argo voyage – this time to Mauritius.

Since mid October, NIWA’s sturdy 28-metre research vessel Kaharoa has deployed 133 high-tech floats at prescribed locations in the South and Eastern Tropical Pacific.

Mud and mangroves in the Firth of Thames

Mud and mangroves in the Firth of Thames

Mangroves have colonised some 600 hectares along the 9 km of coast between the Waitakaruru and Piako River mouths in the southern Firth of Thames.

Mangroves have been spreading across the intertidal flats in the southern Firth of Thames at a rate averaging about 20 m per year during the last 50 years, causing large-scale environmental changes.

Predicting ocean nutrient levels

Predicting ocean nutrient levels

Repeated measurements of temperature and nitrate concentrations were made on transects sailed by Tangaroa and Munida in subtropical (S2 ) and subantarctic (S4) waters and the Subtropical Front (S3) southeast of New Zealand.

Nitrate availability is one of the main factors controlling primary productivity in the world’s oceans. We are using NIWA datasets to better understand variability in concentrations of this important nutrient.

A better picture for oil exploration

A better picture for oil exploration

Oblique view of the Matakaoa Avalanche, north of East Cape, produced with multi-beam swath bathymetry.

Geological processes operating on the seafloor are like a window into the past. With modern marine geoscience technologies, this window can be used to guide exploration for oil reservoirs buried far below.
New Zealand’s oil industry relies on seismic reflection data to find geological structures, such as folds and faults, that can form traps for oil and gas deep beneath the seafloor.

How toxic are heavy metals to estuary life?

How toxic are heavy metals to estuary life?

NIWA scientists Mr David Bremner and Dr Jacquie Reed taking core samples of sediments in the Rangitopuni Estuary, in the upper Waitemata Harbour.

Sediments in some of our urban estuaries have become contaminated with stormwater-derived heavy metals (such as zinc, copper, and lead) and polycyclic aromatic hydrocarbons.
The Auckland Regional Council has recently developed sediment quality guidelines for the Auckland region based on the concentrations of contaminants that are toxic to estuarine organisms.

Research subject: Oceans